The growth of Group III-V materials on silicon (Si) has been pursued for two decades to facilitate the monolithic integration of light emitters with existing Si device technology. One problem has been the formation of a high density of dislocations due to the lattice mismatch between Si and Group III-V materials. Research efforts in the late 1980's demonstrated room-temperature GaAs/AlGaAs lasers and even vertical cavity lasers grown on Si (100). The device characteristics, however, were only marginal due to microcracks and a high dislocation density in the GaAs buffer.
Several growth methods were developed to improve the GaAs buffer, the two most notable of which were a low As/Ga ratio and in-situ thermal cycling. More recently, off-axis substrates and low-temperature growth techniques were invoked to nucleate GaAs growth on Si for InGaAs quantum dot (QD) based lasers. Problems arose, however, because the GaAs buffer was dominated by dark-line defects that originated at the GaAs/Si interface.
Thus, there is a need for lattice-mismatched epitaxy and methods for lattice-mismatched epitaxy that provide defect-free materials on dissimilar platforms.